Journal of Hydraulic Engineering

A three-dimensional hydrodynamic model, MIKE 3, was used to assess the effects of the cooling water thermal plume from the $877\mathrm{MW}$ Charles Poletti power plant that discharges to the East River in Queens, New York City. The East River is a tidal strait that connects New York Harbor and Long Island Sound—two large, out of phase estuaries with complex hydrodynamics. The study was additionally required to account for the thermal discharge of a larger, $1253\mathrm{MW}$ power plant adjacent to Poletti. The model used a flexible mesh formulation based on unstructured triangular elements and was successfully calibrated with triaxial thermal field survey data. After calibration, the model was used to demonstrate that under worst case conditions the resulting thermal plume did not exceed the regulatory thermal criteria.

A planar concentration analysis (PCA) system is used for observing the transport and mixing of a tracer mass in a shallow turbulent free-surface wake flow of a large cylindrical obstacle. The nonintrusive, fieldwise PCA measuring technique is applied to evaluate depth-averaged mass concentrations by making use of light attenuation due to absorption and scattering processes related to a dissolved tracer mass. The scalar fields are decomposed into a low-frequency quasiperiodic part, the coherent flow, and a randomly fluctuating part. From accompanying near-surface velocity measurements, large-scale coherent structures are identified and related to the coherent mass fields. This allows one to assess the role of the large-scale vortices for advection and diffusion in shallow wake flows. The time–mean wake flow displays a self-similar spanwise distribution both for mass and velocity. The longitudinal development of shallow wakes initially shows the growth of unbounded wakes; in the wake far field an attenuated behavior applies.

This paper deals with the development of a new robust fractional-order $PI$ controller for hydraulic canals whose parameters can vary in a wide range. Robustness to gain changes has particularly been increased. A method to design these controllers through the use of frequency specifications is proposed. Analysis of the frequency response of the closed-loop canal shows that the general robustness was also enhanced. Two of these fractional controllers have been experimentally implemented in a laboratory hydraulic canal characterized by time-varying dynamical parameters. A comparison between the real-time responses of the fractional-order control system and those of the standard $PI$ demonstrates the effectiveness of the proposed fractional-order control strategy in terms of performance and robustness.

In this paper, a wavelet-Galerkin method is utilized to solve the hyperbolic partial differential equations describing transient flow in a simple pipeline. Two wavelets (Haar and Daubechies) are utilized as bases for the Galerkin scheme. The governing equations are solved for the expansion coefficients, which are then used to reconstruct the signal at the downstream end of the pipeline; the computed results are in an excellent agreement with those calculated by using the method of characteristics including laminar or linearized turbulent friction terms. Most importantly, the wavelet-Galerkin approach allows the transient flow equations to be solved directly for the expansion coefficients at a certain level of resolution. This can be used to form the wavelet multiresolution framework that can be utilized for further analysis, such as feature extraction and signal identification.

The introduction of nonlinear, shock-capturing schemes has improved numerical predictions of hydraulic bores, but significant numerical oscillations have been reported in the predictions of pipe-filling bore fronts associated with the transition between open-channel and pressurized flow regimes. These oscillations can compromise the stability of numerical models. A study of these oscillations indicates that the strength of the numerical oscillations is associated with the sharp discontinuities in the flow parameters across the jump, particularly the wave celerity. Approaches to attenuate oscillations by artificially reducing acoustic wave speeds may result in the loss of simulation accuracy. Two new techniques to attenuate the oscillation amplitudes are presented, the first based on numerical filtering of the oscillations and the second based on a new flux function that judiciously introduces numerical diffusion only in the vicinity of the bore front. Both approaches are effective in decreasing the strength of the numerical oscillations.

Successive reaches of the Rio Grande have maintained equivalent channel widths of 50 and $250\mathrm{m}$ , respectively, over long periods of time. It is hypothesized that alluvial channels adjust bed slope to match the long-term changes in channel width. Analytical relationships show that wider river reaches develop steeper slopes. A modeling approach using daily water and sediment discharges simulates the transient evolution of bed elevation changes. The analytical and numerical models are in very good agreement with the longitudinal profile measurements of the Bosque del Apache reach of the Rio Grande, NM, from 1992 to 1999. The slope of the $50\mathrm{m}$ wide reach was $50\mathrm{cm}∕\mathrm{km}$ and the slope of the $250\mathrm{m}$ wide reach of the same river increased to $80\mathrm{cm}∕\mathrm{km}$ . This unsteady daily transient model compares well with a steady transient solution at a constant discharge close to the mean annual flow. The transient slope adjustments can also be approximated with an exponential model. Accordingly, it takes about $20–25\text{years}$ for the Rio Grande to achieve about 90% of its slope adjustment.

An experimental study was carried out to understand the local scour process of noncohesive sand beds caused by submerged three-dimensional square jets under model ice covered conditions. The characteristics of asymptotic scour have been investigated by varying the tailwater depth, the densimetric Froude number, the grain size of the bed material, and three different types of water surface conditions (open-water flow, smooth ice covered flow, and rough ice covered flow). Results show that the local scour process under covered conditions is different from that under open water, especially at lower tailwater depths. Further, for the range of test conditions, the effect of the ice cover is reduced when the bed is composed of finer sand particles or when the densimetric Froude number is small.

The Lorenz curve and the Gini index are statistical tools that have been widely used to quantify nonuniformity in economics, ecology, and medicine, but have apparently not been previously applied in hydraulic engineering. In this work, the Lorenz curve was applied to the analysis of sediment transport data from several experiments with natural and lightweight solid particles. The distributions of instantaneous sediment transport rate data have been analyzed, leading to some interesting observations: (1) the values are quite nonuniformly distributed, with a significant proportion of zero values at the lowest sediment transport rates; and (2) the distributions of the values considering only samples with nonzero values are still quite nonuniform; yet the variability of the Gini index with the average sediment transport rate is much smaller than that obtained for the complete data samples, indicating a major role of intermittency in determining the nonuniformity of sediment transport.

Analytical solutions are derived for a one-dimensional model of the bulk temperature response of open-channel flow with unsteady and nonuniform heating at the upstream end, the water surface, and the riverbed. The solutions are explicit formulas comprised of transient terms, which play dominant roles in the upstream region, and equilibrium terms, which determine the temperature far downstream. The applicability of the solutions to practical problems is illustrated for two cases: (1) a stream bounded at its upstream end by a dam and with a midreach inflow; and (2) Boulder Creek, Colo., which is impacted by effluent released from a wastewater treatment plant. The model prediction is in reasonable agreement with gauged data.

Neglecting the effect of well radius may lead to a significant error in the predicted drawdown distribution near the pumping well area. New analytical solutions describing aquifer responses to a constant pumping or a constant head maintained at a finite-diameter well in a wedge-shaped aquifer are derived based on the image-well method and applicable to an arbitrarily located well in the system. The solutions are useful for quantifying groundwater exploitation from a wedge-shaped aquifer and for determining the hydrogeological parameters of a wedge-shaped aquifer in inverse problems.